Landing gear of the type capable of taking two extreme positions, more commonly referred to as "retractable", generally comprises a strut having one end pivoted to the structure of the aircraft, generally about a point or an axis, and its other end having means, such as shock absorber means for example, supporting running means, where "running means" is understood to include any means enabling the aircraft to move on the ground. With such a landing gear structure it is often necessary, for reasons of convenience or of constraint associated with available space, for the wheel to swivel relative to the strut when the landing gear is moved to its "retracted" position in a housing provided or the purpose in the aircraft structure, thereby enabling the wheel to occupy the housing while taking up a minimum amount of space. To do this, some landing gears are designed so that when the landing gear passes from one position to the other, ie. between the "extended" and the "retracted" positions, the low portion of the strut is made to pivot relative to the aircraft structure by means of a secondary crank system controlled by a main rod having one end connected to the aircraft structure, thereby rotating the low portion through an angle which is determined by the shape of the structure. Numerous landing gears of this type exist.
However, it should be observed that the wheel is continuously swivelled between the extreme positions of the landing gear, and thus the opening of the housing has to be large enough for the wheel to be able to enter while it is at some intermediate angle between its extreme positions. Further, auxiliary apparatus necessary for the safety of the aircraft in flight is often to be found inside these housings, eg. pumps and servovalves and other hydraulic devices. That is why it can be advantageous in some cases to provide a landing gear structure in which the wheel's swivelling is programmed to enable it to enter its housing under predetermined conditions.
Preferred embodiments of the present invention provide such landing gear in which the entry angle of the wheel into the aircraft structure can be programmed to a predetermined angle in the range of angles through which the wheel is swivelled as the landing gear is retracted.